Study On Mechanical Properties Of Grilled Reinforced Silty Clay Under Freezing And Thawing Conditions

Seasonal frozen soil is widely distributed in China,accounting for about 53% of China's total land area.The seasonal freezing and thawing process of soil will adversely affect the safety and service life of engineering structures in these areas.The stability of the roadbed is the basis for the normal use of roads,railways,industrial and civil buildings and small-scale water conservancy projects.In the seasonally frozen areas,the softening and instability of the foundations will be caused by the freezing and thawing.Therefore,it is necessary to conduct in-depth study on the effects of soil freezing and thawing.The main factor of the process is to prevent and control freezing and thawing damage.In this paper,the silty clay in the seasonal frozen area is taken as the research object.The soil moisture test,compaction test and particle analysis test are carried out on the soil samples taken,and the basic physical indexes of the soil samples are measured.The influencing factors of the experiment were selected by different water content,compaction degree,reinforced spacing,freeze-thaw temperature,freeze-thaw times and external load under the open conditions for the freeze-thaw orthogonal test to obtain the maximum frost heaving and melting at the top under each freezing and thawing condition.The displacement value and the change of the moisture content at each height and the internal pressure of the soil at the end of the melting state.The SPSS software was used to fit the orthogonal experimental data to obtain the maximum linear heave,the displacement and the pressure change.The multiple linear regression equations were expressed by various influencing factors.The factors of the fitting equation were used to determine the interaction between each factor and each factor.The effect of the effect on the frost heave displacement,the melt and sink displacement and the pressure change;the primary and secondary relations affected by each factor are judged by the normalization coefficient.The MATLAB software is used to solve the equation optimally,and the values of each factor and the corresponding target value are obtained when each target value is small.The statistical results show that the soil can be divided into six stages: constant temperature stage,freezing stage,frost heaving stage,frost heaving stage,melting stage and melting stage.In the stage of frost heaving and the stage of melting and sinking,there will be a stage of rate change.Due to the deformation of the soil in the soil,the deformation of the soil is inhibited,and the frost heaving of the soil is suppressed.The change of displacement after soil freezing and thawing is more closely related to the change of water content in the upper part of the soil.The displacement change is positively correlated with the water content.During the freeze-thaw cycle,when the soil moisture content is low,the phenomenon of “thermal expansion and contraction” will occur at the initial stage of freezing and thawing,which is exactly the opposite of the change of the sample with high water content,but the soil passes through the soil after freezing and thawing.The water content of the body structure increases,and eventually it will exhibit the phenomenon of “frozen expansion and sinking”,and the compressive capacity of the soil decreases.Regression analysis of frost heaving displacement and freeze-thaw internal pressure changes,the most significant factor affecting the melting and sinking displacement is the interaction between water content and external load.The effect of reinforcement spacing on soil frost heave displacement is the most significant.The significant factor affecting the pressure change is the degree of compaction;when controlling the freezing and thawing deformation of the soil,the effect of reinforced is more significant under the combination of compaction and reinforced spacing,and the best compaction should be selected according to the number of layers.In the range of experimental factors,the fitted regression equation was solved by MATLAB software.When the number of freeze-thaw cycles was 5,the freezing temperature was-15?and the external load was 30 k Pa,the initial moisture content of the soil was 16%.When the compaction degree is 90% and the reinforced spacing is 25 cm,the soil displacement and pressure change are the smallest,which is the optimal combination.Through the comprehensive study of multi-factors of soil,the fitting regression equation is closer to the actual situation.The optimal solution of different soils in different regions can be reasonably designed according to the optimal solution of the equation,which provides a reference for practical engineering.